In an insulated-type power semiconductor module used for a power conversion device such as an inverter, a wiring pattern is formed on a metal plate serving as a heat-radiation plate with an insulating substrate interposed therebetween. On this wiring pattern, a power semiconductor element is provided and connected to an electrode terminal with a wire bond or the like. This power semiconductor element is sealed with resin.
In the power semiconductor module performing a switching operation at a large current and a high voltage, a surge voltage ΔV=L·di/dt is applied to the power semiconductor element according to a time change rate di/dt of the current achieved when the power semiconductor element is turned off and according to a parasitic inductance L included in the power conversion device. When the parasitic inductance is relatively large, a surge voltage exceeding a breakdown voltage of the power semiconductor element is generated, which may lead to breakage of the power semiconductor element. Accordingly, the power conversion device needs to be reduced in inductance and the power semiconductor module also needs to be reduced in inductance.
The power semiconductor module having a positive arm and a negative arm provided in its package includes elements exhibiting a relatively large inductance. These elements may be a positive electrode, a negative electrode, and an output (alternating-current (AC)) electrode that are connected to an external circuit.
Thus, in recent years, electrodes provided within a module are stacked, so that the magnetic flux is cancelled between the electrodes when a current flows therethrough, thereby implementing inductance reduction (for example, PTD 1).